M2 Driven Element Design

M2 appears to have the right idea about driven element design. It's much more rugged than the K1FO driven element design. The standoffs get broken and flexing causes strains that break the fragile wire connecting to the UG-141 coax. The picture below comes from a Directive Systems product photo.


Here's a picture of an M2 Antenna Inc. two meter driven element phasing block.

The phasing line uses RG-6 and F connectors, which seems wrong to hams. But, modern F connectors come with multiple O rings for waterproofing and cheap tools for assembly. The RG6 doesn't limit power handling because most of the power couples to the phased element by radiation and conduction around the folded dipole. Also, the 70 ohm impedance doesn't matter because the line is 1/2 wave long.

The 1/4 inch elements feed into the block through 1/2 inch delrin rods about 5/8 inch long. The delrin rod is drilled for the elements. A set screw pinches the delrin and the element to hold it in place. It's not clear how the tolerances ensure that this part of the design remains waterproof.

M2 describes their driven element design well.

The heart of these antennas is a driven element module originally designed for maritime ATS satellite service. All connectors are O-ring sealed to the CNC machined block. Internal connections are sealed with a space-age silicone gel with nearly 4 times the dielectric strength of air. The balun connectors are triple sealed on the coax and nut-sealed at the block connectors.

A closeup of the connections in the hole show an 18 gauge wire pushed into the F connectors and a somewhat larger wire connected to the elements. It appears that the end of 1/4 inch elements gets drilled, a wire inserted and probably pinched.



The driven element block connects to the boom with a single screw and a curved cutout to align the assembly.